job, that's your best weapon. if they said, "go and run and smash into the wall", i would do it for the sport. >> blake did it all his life. he started to question it after suffering three concussions. >> the third, which is the one where i realised something was wrong, was here. it was, "oh", and you start to get dizzy. >> dizzy, foggy. >> yes. were. >> what's crazy is the coach came up and said, "great job", i did my job and had to sacrifices my brain to do it. >> when a player gets a concussion blow, the brain moves rapidly, the brain bouncing around in the skull. the nfl reports 50 players have been sidelined by concussions.